Oh yeah it's written on the board...
Will such a step attenuator work well? Can it be connected in series before the amp input without the filters?
Will such a step attenuator work well? Can it be connected in series before the amp input without the filters?
What dimensions of heatsink should I use? The data I have is 0.65 c\w heatsink, but I find it hard to translate it to aluminium heatsink overall and fin dimensions.
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Another question: if I opt to go with a single transformer, does it have to be double the amperage, that is 600W?
Heatsinks sold by their manufactures are all rated in temperature rise per watt of dissipation (deg C/W or degF/W). If you buy from other sources, its like buying a resistor that has no power rating.
You can only guess when you buy heatsinks by their dimensions only. Shallow, close pitch fins for example, don't cool as well as deep, wide pitch tapered fins. Obviously, if your vendor has no clue and no ratings for their heatsinks, you buy at your risk.
Use a reputable source and your heatsinks will be rated, as are my local manufacturer's. Conrad Heatsinks - Technical Details
More generally, it seems that you need to read up on the subject of audio electronics. There are a couple of excellent books written by members for global publication and also DIYaudio member rode's website has many articles and support products pitched at different levels of ability but giving lots of useful in-depth information on your questions too.
You can use a single transformer with dual secondaries.😉
I would not go lower than 300vac and for secondaries, I would go for 40V. remember their supply voltage range is 35vdc-60vdc.
I only found this local supplier for heatsink profiles which cuts them to length per order. I now have to find a section which is similar to one which I know the rating of.
Your amp looks much smaller than the others, how could the heatsinks dissipate enough heat? Are you driving with a very small load?
I'm not sure I understand. Does it mean if I go from dual mono to single stereo transformer, what do I have to change? The rating of the current should be 6A instead of min. 3A? That means the power rating should be double as well, min. 600VA...
Your amp looks much smaller than the others, how could the heatsinks dissipate enough heat? Are you driving with a very small load?
I'm not sure I understand. Does it mean if I go from dual mono to single stereo transformer, what do I have to change? The rating of the current should be 6A instead of min. 3A? That means the power rating should be double as well, min. 600VA...
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That's fine as the supplier should know or be able to find out all the appropriate ratings.
It's important that the fin types are suitable for the duty. i.e big, deep fins mounted vertically for static, convection cooling and you can use finer, shallow fins in any orientation if using fan forced cooling. Obviously, the heatsink rating will depend on air velocity when fan cooling is used. It requires experimentation to get that right.
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They only cut to length, they don't have ratings. So if this heatsink is rated 0.67C/W, I should order this 16cmx4cm heatsink cut to 10cm length?
I have 200 by 40 by 100 high with 20 fins and they are rated 0.55C/W when the sink is 70C degrees above ambient.
Your slightly smaller 160 by 40 by 100 high with 16 fins should be around the 0.65 to 0.7 C/W when it is ~70C above ambient.
Your slightly smaller 160 by 40 by 100 high with 16 fins should be around the 0.65 to 0.7 C/W when it is ~70C above ambient.
I went for the smallest design as possible, D12 W8 H3 (all in inches). The heat sinks get warm and I use the chassis as heat sink too. I used a 300vac with dual 32v secondaries. I get around 80 watts per channel that is way enough for me.
Is it possible to use a 3 positions on switch where the middle position charges the caps through a resistor?
Do you mean a bleeder resistor?
I do not know "why" you want to put a three way switch😕
These amp kits are as quiet as a mouse! You will not....I repeat, You will not hear a pop at turn on or off! These amp kits are "very" well design.
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I think the OP is suggesting a manual soft-start switch which temporarily inserts power resistors in the DC rails from the rectifiers.
Half the switch then has to operate at AC mains power and the rest at DC rail voltages. This would require a special switch assembly and
is likely a really bad idea, safety wise. It could even be implemented with suitable DC and AC rated relays but there is an easier way.
Fitting a standard soft start kit, limiting inrush current on the AC mains side would be a better, automatic and proven method,
provided proper mains voltage insulation is fitted and approved wiring practice is used.
However, it's folly to think that slowly raising the DC power rails will prevent thumps. Thumps are due to different relative voltage changes within the amplifier and may just as easily occur on turn-off as turn-on if the design is prone, as many now are, seeing relays are used by default for a number of purposes so you can't avoid them in commercial products.
The point is, that this design is not prone to thumps, so it doesn't need a muting relay.
Half the switch then has to operate at AC mains power and the rest at DC rail voltages. This would require a special switch assembly and
is likely a really bad idea, safety wise. It could even be implemented with suitable DC and AC rated relays but there is an easier way.
Fitting a standard soft start kit, limiting inrush current on the AC mains side would be a better, automatic and proven method,
provided proper mains voltage insulation is fitted and approved wiring practice is used.
However, it's folly to think that slowly raising the DC power rails will prevent thumps. Thumps are due to different relative voltage changes within the amplifier and may just as easily occur on turn-off as turn-on if the design is prone, as many now are, seeing relays are used by default for a number of purposes so you can't avoid them in commercial products.
The point is, that this design is not prone to thumps, so it doesn't need a muting relay.
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I do not understand WHY people sometimes get so complicated to them-self...Just use a thermistor and that is it😉
I supposed I could use one of those: Amplifier Board Sound Power Start Protection High Power Soft Start Board | eBay
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